Sylvester Stallone - The Italian Stallion earned his nickname the hard way in a softcore skin flick called "The Party at Kitty and Stud's" that was released in 1970 -- six years before "Rocky" made him a household name.

Getty Images

Sasha Grey - This hardcore porn starlet went legit with Steven Soderbergh's experimental drama "The Girlfriend Experience," which led to roles in several other mainstream movies, including "I Melt With You" and "Open Windows."

Getty Images

Jackie Chan - From the Bronx to the bedroom, Jackie Chan has rumbled everywhere, including a 1975 Hong Kong movie called "All in the Family" that includes one of only two sex scenes featuring the martial arts master.

Getty Images

Joanie Laurer - Best known as Chyna, one of the WWE's marquee wrestling stars, she retired from the ring and entered the adult film industry, starring in the sex tape "One Night in China" and the XXX movie "Backdoor to China."

New World Pictures

Marilyn Chambers - She worked with director David Cronenberg and "Friday the 13th" producer Sean S. Cunningham before building herself into an adult-oriented brand and becoming one of the faces of the XXX movie biz.

Getty Images

Traci Lords - This teenage sex goddess got off her back to work with John Waters on "Cry-Baby" and "Serial Mom," and she never looked back other than to co-star in Kevin Smith's 2008 movie "Zack and Miri Make a Porno."

Getty Images

Simon Rex - He starred in a series of porn movies, including "Young, Hard and Solo II and III," that were aimed at gay audiences well before he landed roles in the TV series "Felicity" and "Jack & Jill" and a bunch of "Scary Movie" sequels in the 2000s.

Getty Images

Tom Sizemore - The "Saving Private Ryan" star showed his own privates online via his website XXXtom.com - which saw him embracing his porn-ready last name.

Getty Images

Ron Jeremy - The Hedgehog, as he's affectionaly known, showed his legitimate acting chops in Adam Rifkin's comedy "Homo Erectus," as well as edgy indies such as "Spun" and "The Rules of Attraction."

Getty Images

Sibel Kekilli - The German actress who plays Shae on HBO's "Game of Thrones" got her start in porn, performing under the name Dilara.